College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China; Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, Hubei, 430223, China.
Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, Hubei, 430223, China.
Fish Shellfish Immunol. 2024 Dec;155:110019. doi: 10.1016/j.fsi.2024.110019. Epub 2024 Nov 8.
Largemouth bass ranavirus (LMBRaV), also known as largemouth bass virus (LMBV), is a highly damaging viral pathogen that causes widespread mortality in cultured largemouth bass and poses a significant threat to the farming industry in China. However, there is a paucity of effective preventive methods for this disease by LMBRaV. Research has established that herbal extracts possess antiviral activity, potentially exerting a controlling effect on viruses in aquaculture. Therefore, the identification of simple and structurally safe herbal extract immunomodulators is critical for largemouth bass health and development. Rhein, an herbal compound, exhibits a broad spectrum of pharmacological effects in herbal medicine. This study aimed to evaluate the properties and effects of rhein against LMBRaV in epithelioma papilloma cyprinid (EPC) and largemouth bass. In vitro CCK-8 assays were performed to determine the highest safe concentrations. Significantly, 50 mg/L rhein effectively inhibited cytopathic effects (CPE) in EPC induced by LMBRaV, resulting in a 97 % reduction in viral replication rates. Furthermore, a six-point dose-response experiment revealed that rhein doses as low as 6.4 mg/L inhibited LMBRaV and suppressed LMBRaV infection with a dose-dependent manner. Subsequent experiments demonstrated that sustained rhein activity effectively alleviated CPE and nuclear damage caused by LMBRaV infection. Additionally, rhein exerted protective effects against declines in LMBRaV-induced mitochondrial membrane potential. In vivo experiments validated that largemouth bass diets supplemented with 0.075 % rhein exerted a protective effect against LMBRaV infection. Moreover, LMBRaV MCP gene expression levels were lower in several organs of fish in the rhein supplementation group. Immunogene analysis determined that rhein upregulated relevant gene expression levels in multiple organs of largemouth bass, with higher activities observed for the Mx, INF-γ, and IRF3 genes. Histopathological results displayed that a supplemental dosage of 0.075 % rhein significantly mitigated LMBRaV infection-induced pathological damage in the liver, spleen, and kidney. Taken together, these in vivo and in vitro results support the effective use of rhein as a promising candidate for the development of antiviral treatment against LMBRaV infection, highlighting its role in aquatic animal husbandry as a wide-spectrum antiviral and immune response booster.
大口黑鲈虹彩病毒（LMBRaV），又称大口黑鲈病毒（LMBV），是一种高度破坏性的病毒病原体，可导致养殖大口黑鲈广泛死亡，并对中国的养殖产业构成重大威胁。然而，目前针对这种疾病，缺乏有效的预防方法。研究已经证实，草药提取物具有抗病毒活性，可能对水产养殖中的病毒产生控制作用。因此，识别简单且结构安全的草药提取物免疫调节剂对于大口黑鲈的健康和发展至关重要。大黄是一种草药化合物，在草药医学中具有广泛的药理作用。本研究旨在评估大黄对鲤鱼上皮瘤细胞（EPC）和大口黑鲈中 LMBRaV 的性质和作用。通过体外 CCK-8 测定法确定最高安全浓度。显著的是，50mg/L 的大黄可有效抑制 LMBRaV 诱导的 EPC 的细胞病变效应（CPE），使病毒复制率降低 97%。此外，六剂量反应实验表明，大黄的剂量低至 6.4mg/L 即可抑制 LMBRaV 并以剂量依赖的方式抑制 LMBRaV 感染。后续实验表明，大黄的持续活性可有效缓解 LMBRaV 感染引起的 CPE 和核损伤。此外，大黄对 LMBRaV 诱导的线粒体膜电位下降具有保护作用。体内实验验证了在大口黑鲈的饮食中添加 0.075%的大黄可对 LMBRaV 感染起到保护作用。此外，在添加大黄的鱼的几个器官中，LMBRaV MCP 基因的表达水平降低。免疫基因分析确定大黄可上调大口黑鲈多个器官的相关基因表达水平，其中 Mx、IFN-γ 和 IRF3 基因的活性更高。组织病理学结果显示，添加 0.075%的大黄剂量可显著减轻 LMBRaV 感染引起的肝脏、脾脏和肾脏的病理损伤。总之，这些体内和体外结果支持将大黄有效用作开发针对 LMBRaV 感染的抗病毒治疗的有前途的候选物，突出了其作为广谱抗病毒和免疫反应增强剂在水产养殖中的作用。
